To Fill In
Transitive verb and Ichidan verb
かきいれる
この書類のここに社会保証番号を書き入れてもらえれば、あとは全て上手くやっておきますよ。
If you could fill in your social security number here in this document, I can take care the rest.
けっこん証明書に名前を書き入れました。
I wrote in my name on the marriage certificate.
日本語の学習予定を書き入れるTofugu手帳をコウイチに作ってもらいたいな。
I want Koichi to make a Tofugu notebook so that we can write our Japanese study schedules in it.
To insert what you write into something is to write in or to fill in.
The readings come from 書く and 入れる. Combine those two words to get the reading of this word.